The present invention is generally directed to fault indicators, and more particularly, to a test-point mounted fault indicator which has a high degree of immunity to false fault indications brought about by fault currents occurring in adjacent conductors.
Various types of fault indicators have been constructed for detecting electrical faults in power distribution systems, including clamp-on type fault indicators, which mount on a cable of the system, and test-point mounted fault indicators, which typically mount on a test point incorporated in a system component.
Test-point mounted fault indicators typically mount within an integral test point socket of a plug-in elbow connector of the type used in high voltage alternating current power distribution systems for establishing a plug-in connection to a transformer or other system component. These fault indicators typically derive their operating power by a capacitive coupling to the conductor of the connector, and utilize a reed switch in magnetic communication with the monitored conductor to sense a fault current in the conductor.
These prior test-point mounted fault indicators, while providing satisfactory performance in many applications, were subject to false fault indications in response to fault currents in adjacent conductors when installed in tight spaces having many cables supplying different loads, as in, for example, a switchboard serving a number of heavy loads.
The present invention overcomes this drawback by providing as an integral part of the test-point mounted fault indicator a novel shielded core assembly which encircles the body of the elbow connector, and hence the monitored conductor. By reason of this shielding, the fault indicator of the invention can be mounted in a confined area adjacent other conductors.
Accordingly, it is a general object of the present invention to provide a new and improved fault indicator for use in close proximity to other conductors.
It is a specific object of the present invention to provide a fault indicator for mounting a test point on an elbow connector which has improved immunity to fault currents in adjacent conductors.